Member for a Plasma Processing Apparatus and Method of Manufacturing the Same

ABSTRACT

A member for a plasma processing apparatus, which is excellent in film-formability, durability, and reliability, is provided. 
     On a substrate, a ceramic film having a purity not less than 98% is provided. In the ceramic film, grains constituting the film have a grain diameter not greater than 50 nm and the amount of moisture released from the film is not more than 10 19  molecules/cm 2 .

TECHNICAL FIELD

This invention relates to a member for a plasma processing apparatus formanufacturing an electronic component, such as a semiconductor deviceand a liquid crystal panel, and to a method of manufacturing the same.

BACKGROUND ART

As a process of manufacturing a semiconductor device, a liquid crystalpanel, and the like, there are a film forming process and a dry etchingprocess which are carried out by plasma processing on a Si wafer and aglass substrate. Upon the plasma processing, various corrosive gases areused. A conventional chamber inner wall is made of metal and exposed inan uncovered state inside a chamber. However, with recent improvement ofan integration degree of the semiconductor device and the like, apermissible level of metal contamination is becoming extremely low.Further, in order to achieve a higher quality of the plasma processing,plasma having a higher density is used year after year.

Therefore, as a member exposed inside the chamber (plasma processingchamber) in a plasma processing apparatus, a ceramic sintered body isbecoming used which exhibits high corrosion resistance against theplasma and the corrosive gases. For example, an electronic componentmanufacturing apparatus disclosed in Patent Document 1 uses a memberusing the ceramic sintered body.

It has been comparatively easy to manufacture the plasma processingchamber having a size corresponding to 5-inch and 6-inch Si wafers by amember made of the ceramic sintered body. However, it is extremelydifficult to manufacture a recent large-scaled plasma processing chambercorresponding to 8-inch and 12-inch Si wafers and a large-sized liquidcrystal substrate by the member made of the ceramic sintered body. Thisis attributed to a problem of a low yield and a high manufacturing cost.

Under the circumstances, for the plasma processing chamber, use is madeof a member comprising a metallic substrate low in cost, excellent inworkability, and easily increased in size and a ceramic film formed onthe substrate by using a spraying method. Such a member has corrosionresistance similar to that of the ceramic sintered body. For example, anelectronic component manufacturing apparatus disclosed in PatentDocument 2 has a member obtained by forming a ceramic film (sprayedfilm) by using the spraying method.

In the spraying method, ceramic powder having a high melting point ismelted by electric energy or gas energy and sprayed onto a substrate.Therefore, insufficient melting of a ceramic material is easily causedto occur. In case where melting of the ceramic material is insufficient,open pores or consecutive pores are generated on the sprayed film. Also,countless microcracks are generated on the sprayed film due to quenchingfrom a molten state. In a plasma processing chamber manufactured byusing the member having the sprayed film, when a corrosive gas andplasma are brought into contact with the sprayed film, the corrosive gaspenetrates the consecutive pores or the microcracks of the sprayed filmto cause corrosion of the substrate to occur. Eventually, there arises aproblem of peeling of the sprayed film or the like. Further, in thespraying method, the sprayed film is formed to have a thickness of 100μm or more in order to cover those defects due to the countless pores ormicrocracks. Between such a thick sprayed film and the metallicsubstrate, mismatch in linear expansion coefficient occurs. Afterrepetition of temperature rising and cooling in plasma processing, thesprayed film is peeled off due to the mismatch in linear expansioncoefficient.

In view of the above, it is proposed to form the ceramic film by PVD orCVD instead of the sprayed film. However, in both of the methods, it isrequired to provide a vacuum environment at the time of film formation,to controllably position a material nozzle at a fixed distance from asurface on which the film is to be formed, and to heat the substrate toa high temperature. Therefore, these techniques are not effective as amethod of manufacturing a member for a large-sized andcomplicated-shaped plasma processing apparatus.

Alternatively, it is proposed to form the ceramic film by preparing asolution (sol) in which a metallic compound or a fine powder rawmaterial is dispersed, applying the solution to a surface of thesubstrate by a simple device, such as a spray nozzle, and carrying outheat treatment. Such a method is called a sol-gel method. Although themethod is a prior and existing technique, it is possible to form aceramic film excellent in film formability, durability, and reliability.

Patent Document 1: JP-B-3103646

Patent Document 2: JP-A-2001-164354

Non-Patent Document 1: “Sintering of Ceramics” written by YusukeMoriyoshi et al, published by Uchida Rokakuho on Dec. 15, 1995

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

However, use of the sol-gel method as a method of forming the ceramicfilm of the member for a plasma processing apparatus has the followingproblems.

The ceramic film of the member for a plasma processing apparatus isrequired to have a purity not less than 98%. When the sol-gel method isexecuted by using a high purity material, heat treatment at a hightemperature (for example, 700° C. or higher) is required.

However, as the substrate of the member for a plasma processingapparatus, a substrate made of Al is often used. Since Al has a lowmelting point (approximately 600° C.), the substrate made of Al issusceptible to deformation or composition change if it is exposed to atemperature not lower than 400° C.

Alternatively, in order to execute the sol-gel method at a lowtemperature capable of preventing deformation or composition change ofAl, it is necessary to mix various impurities, such as alkali metal andheavy metal, into a sol or to form a glass layer in the film. In thiscase, a high purity ceramic film having high corrosion resistance cannot be formed. Further, in the ceramic film formed at a comparativelylow temperature, bonding strength between granular components is low.Therefore, generation of particles is highly possible.

Thus, heretofore, when the sol-gel method is used as a method ofmanufacturing the member for a plasma processing apparatus in order toobtain the member excellent in film formability, durability, andreliability, there is a problem in obtaining a high purity ceramic filmand in preventing deformation or composition change of a substrate madeof low-melting-point metal.

It is therefore an object of the present invention to solve the problemin the conventional technique and to provide a member for a plasmaprocessing apparatus, which is excellent in film formability,durability, and reliability.

It is another object of the present invention to provide a method ofmanufacturing a member for a plasma processing apparatus, which iscapable of manufacturing such a member as mentioned above.

Means to Solve the Problem

According to the present invention, at least the following aspects (1)through (24) are obtained.

(1) A member for a plasma processing apparatus, the member comprising asubstrate and a ceramic film formed thereon and having a purity not lessthan 98%, in which the ceramic film is constituted by grains having agrain diameter not greater than 50 nm, the amount of moisture releasedfrom the film being not more than 10¹⁹ molecules/cm².

(2) The member for a plasma processing apparatus according to the aspect(1), the member comprising, as the ceramic film, a sol-gel film formedby a sol-gel method.

(3) The member for a plasma processing apparatus according to the aspect(1), in which the substrate is made of metal, ceramics, glass, or acomposite material thereof, the ceramic film being a film comprising atleast one kind of element selected from group II-VI elements, groupXII-XIV elements, and rare-earth elements in the periodic table.

(4) The member for a plasma processing apparatus according to the aspect(1), in which the ceramic film is a film comprising at least one kind ofelement selected from Mg, Al, Si, Ti, Cr, Zn, Y, Zr, W, and therare-earth elements.

(5) The member for a plasma processing apparatus according to the aspect(1), in which the ceramic film has translucency represented by atransmittance not less than 80% in a visible light range at a wavelengthbetween 400 and 800 nm when a film thickness is not greater than 5 μm.

(6) The member for a plasma processing apparatus according to the aspect(1), in which the ceramic film is formed in an oxygen-containingatmosphere in a temperature range between 250 and 1200° C.

(7) The member for a plasma processing apparatus according to the aspect(1), in which the ceramic film has a purity not less than 99.5%.

(8) The member for a plasma processing apparatus according to the aspect(1), in which the substrate is made of metal, the substrate beingprovided with a film formed on its surface and obtained by passivationof the surface of the substrate.

(9) The member for a plasma processing apparatus according to the aspect(1), in which the substrate is made of aluminum, the substrate beingprovided with an anodic oxidation film formed on its surface.

(10) The member for a plasma processing apparatus according to theaspect (1), in which the substrate is made of metal, the substrate beingprovided with a film formed on its surface by heat treatment.

(11) The member for a plasma processing apparatus according to theaspect (1), the member comprising, as the ceramic film, a sprayed filmformed on the substrate by a spraying method and a sol-gel film formedon the sprayed film by a sol-gel method.

(12) The member for a plasma processing apparatus according to theaspect (1), the member comprising, as the ceramic film, a sol-gel filmformed on the substrate by a sol-gel method and a sprayed film formed onthe sol-gel film by a spraying method.

(13) The member for a plasma processing apparatus according to theaspect (1), in which the substrate has a plate-like shape having pores,a tubular shape, or a container shape.

(14) A method of manufacturing a member for a plasma processingapparatus, comprising the step of forming a ceramic film having a puritynot less than 98% on a substrate, in which the forming of the ceramicfilm is carried out so that grains constituting the film have a graindiameter not greater than 50 nm and the amount of moisture released fromthe film is not more than 10¹⁹ molecules/cm².

(15) The method of manufacturing a member for a plasma processingapparatus according to the aspect (14), in which, as the ceramic film, asol-gel film is formed by a sol-gel method.

(16) The method of manufacturing a member for a plasma processingapparatus according to the aspect (14), comprising the steps of formingthe substrate made of metal, ceramics, glass, or a composite materialthereof; and forming, as the ceramic film, a film comprising at leastone kind of element selected from group II-VI elements, group XII-XIVelements, and rare-earth elements in the periodic table.

(17) The method of manufacturing a member for a plasma processingapparatus according to the aspect (14), comprising the step of forming,as the ceramic film, a film comprising at least one kind of elementselected from Mg, Al, Si, Ti, Cr, Zn, Y, Zr, W, and rare-earth elements.

(18) The method of manufacturing a member for a plasma processingapparatus according to the aspect (14), in which the ceramic film isformed in an oxygen-containing atmosphere in a temperature range between250 and 1200° C.

(19) The method of manufacturing a member for a plasma processingapparatus of the aspect (14), in which the ceramic film has a purity notless than 99.5%.

(20) The method of manufacturing a member for a plasma processingapparatus of the aspect (14), comprising the steps of forming thesubstrate made of metal; and forming, on a surface of the substrate, afilm obtained by passivation of the surface of the substrate.

(21) The method of manufacturing a member for a plasma processingapparatus of the aspect (14), comprising the steps of forming thesubstrate made of aluminum; and forming an anodic oxidation film on asurface of the substrate.

(22) The method of manufacturing a member for a plasma processingapparatus of the aspect (14), comprising the steps of forming thesubstrate made of metal; and forming a film formed by a heat treatmenton a surface of the substrate.

(23) The method of manufacturing a member for a plasma processingapparatus of the aspect (14), comprising, as the forming of the ceramicfilm, the steps of forming a sprayed film on the substrate by a sprayingmethod and forming a sol-gel film on the sprayed film by a sol-gelmethod.

(24) The method of manufacturing a member for a plasma processingapparatus of the aspect (14), comprising, as the forming of the ceramicfilm, the steps of forming a sol-gel film on the substrate by a sol-gelmethod and forming a sprayed film on the sol-gel film by a sprayingmethod.

EFFECT OF THE INVENTION

The member for a plasma processing apparatus according to the presentinvention is excellent in film formability, durability, and reliability.

The sol-gel film in the present invention is highly dense and highlyflat and smooth and therefore has high plasma resistance in a highdensity plasma environment. Further, also in a corrosive gas environmentand in a chemical environment, the sol-gel film exhibits high gasresistance and high chemical resistance because the film is highly denseso as to protect a substrate.

In the conventional technique, uniform film formation onto a complicatedconfiguration, an inner surface of a pipe, or the like is impossible.According to the present invention, film formation is easily performedby pouring a liquid sol or by dipping.

Further, by forming the highly dense sol-gel film on a surface of asprayed film, particle generation from the sprayed film can besuppressed.

Furthermore, when a composite film obtained by pretreatment or surfacetreatment of the sprayed film or a composite film having a sandwichstructure is exposed to a corrosive gas, peeling of the sprayed film canbe suppressed because the dense sol-gel film blocks the corrosive gas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph for describing a characteristic of a member for aplasma processing apparatus according to a first example of the presentinvention, showing measurement data of the amount of moisture releasedfrom an Y₂O₃ film.

FIG. 2 is a graph for describing the characteristic of the member for aplasma processing apparatus according to the first example of thepresent invention, showing the amount of moisture released at each oftemperature rising stages.

FIG. 3 is a graph for describing the characteristic of the member for aplasma processing apparatus according to the first example of thepresent invention, showing a relationship between a firing temperatureand the amount of moisture released when a temperature is increased upto 500° C.

FIG. 4 is a schematic sectional view showing a member for a plasmaprocessing apparatus according to a second example of the presentinvention.

FIG. 5 is a schematic sectional view showing a member for a plasmaprocessing apparatus according to a third example of the presentinvention.

FIG. 6 is a schematic sectional view showing a member for a plasmaprocessing apparatus according to a fourth example of the presentinvention.

FIG. 7 is a schematic sectional view showing a member for a plasmaprocessing apparatus according to a fifth example of the presentinvention.

FIG. 8 is a schematic sectional view showing a member for a plasmaprocessing apparatus according to a sixth example of the presentinvention.

FIG. 9 is a schematic sectional view showing a member for a plasmaprocessing apparatus according to a seventh example of the presentinvention.

FIG. 10 is a table showing evaluation results for the members for aplasma processing apparatus according to the present invention togetherwith evaluation results for comparative examples.

FIG. 11 is a graph for describing a characteristic of the member for aplasma processing apparatus according to the example of the presentinvention, showing a transmittance of a sample 10 as the example at avisible light wavelength in a range between 400 and 800 nm.

FIG. 12 is a graph for describing a characteristic of the member for aplasma processing apparatus according to the example of the presentinvention, showing a transmittance of a sample 11 as the example at avisible light wavelength in a range between 400 and 800 nm.

FIG. 13 is a graph for describing a characteristic of the member for aplasma processing apparatus according to the example of the presentinvention, showing a transmittance of a sample 12 as the example at avisible light wavelength in a range between 400 and 800 nm.

FIG. 14 is a graph for describing a characteristic of the member for aplasma processing apparatus according to the example of the presentinvention, showing a transmittance of a sample 37 as a comparativeexample at a visible light wavelength in a range between 400 and 800 nm.

BEST MODE FOR EMBODYING THE INVENTION

A member for a plasma processing apparatus according to the presentinvention has a ceramic film which is formed by a sol-gel method, whichhas a purity not less than 98%, and which has plasma resistance andcorrosive gas resistance.

Further, a method of manufacturing a member for a plasma processingapparatus according to the present invention comprises a step of forminga ceramic film on a substrate by the sol-gel method, which has a puritynot less than 98% and has plasma resistance and corrosive gasresistance.

Specifically, according to the present invention, there is provided amember for a plasma processing apparatus, which comprises a substratemade of a material, such as metal, ceramics, and glass, generally usedas a structural material and having a surface coated with a ceramic filmmade of an oxide formed of group II-VI elements, group XII-XIV elements,and rare-earth elements, or a composite oxide formed of two or morekinds of the above-mentioned elements. In this technique, the sol-gelmethod is used. By coating the substrate by using a spraying method, adipping method, or the like, and then performing heat treatment in anoxygen-containing atmosphere at a temperature not lower than 250° C.,oxide ceramics can be obtained.

For the spraying method, use of a specially designed and optimizednozzle is recommended. Instead, also by using an airbrush and a spraygun commercially available, a similar film can be obtained. The dippingmethod is a method of coating a substrate surface with a uniform solfilm by dipping a substrate into a solution and thereafter pulling outthe substrate at a low speed (10 to 50 mm per minute) and at a constantrate.

As a heat treatment condition, it is necessary to heat at a firingtemperature between 250 and 1200° C. for 1 to 5 hours by using an ovenor an electric furnace.

Further, this technique is characterized in that a ceramic thin filmhaving a high purity from 98% to 99.99% can be obtained at such a lowtemperature of 250° C.

Other than direct film formation onto the substrate, the above-mentionedtechnique is applicable to composite formation by surface coating onto asprayed film, composite formation by application of a sprayed film afterformation of a sol-gel film on a substrate, and a composite film formedby film formation for passivation of a substrate, such as an anodicoxidation film and a fluoride film.

Incidentally, a grain diameter of the sol-gel film in the presentinvention was observed by using a field-emission-type scanning electronmicroscope (JEM-6700F manufactured by JEOL Ltd.). As a result, it wasconfirmed that all grains constituting the film had a grain diameter notgreater than 50 nm. In a conventional film formation method, a graindiameter of a ceramic film is not smaller than 100 nm. In contrast, inthe present invention, by achieving a grain diameter not greater than 50nm, it is possible to perform film formation with a high purity (98% ormore) and at a low temperature of 250° C. This is because, bymicroparticulation of the sol-gel film into a grain diameter of 50 nm orless, a sintering temperature is drastically lowered and sintering isstarted at approximately 250° C. Non-Patent Document 1 describes that,as grains become smaller, grain boundary diffusion and volume diffusioncontributing to sintering are relatively increased and this relationshipis extremely effective when a material having a high steam pressure anddifficult to be densified is sintered and that, when a grain diameterbecomes smaller, the number of contact points per unit volume isincreased and the number of generation points and disappearance pointsof atoms involved in mass transfer is increased, thereby providing astate preferable for densification. Thus, even at a low processingtemperature lower than 700° C., a high purity can be achieved only bythe sol-gel method.

EXAMPLES

Hereinbelow, a member for a plasma processing apparatus and a method ofmanufacturing the member for a plasma processing apparatus according toexamples of the present invention will be described with reference tothe drawing.

Samples 1 to 29 as examples of the present invention and samples 31 to37 as comparative examples were manufactured. For those samples, somecharacteristics were verified and evaluated. Results thereof are shownin a table of FIG. 10.

Each of the samples 1 to 29 as the examples of the present inventioncomprises a substrate made of one of various materials shown in asubstrate-column in the table and having a 50 to 200 mm square size anda ceramic film formed on a surface of the substrate by a film formationmethod including at least a sol-gel method. By a device used in formingthe ceramic film by the sol-gel method, film formation was carried outby spraying a sol as a raw material onto the substrate by a spraynozzle. Further, an electric furnace was used for heat treatment.

First Example

As measurement of a basic property of the ceramic film of the presentinvention, the amount of moisture released from a ceramic film formed ona Si substrate was observed. The amount of released moisture wasmeasured by an atmospheric pressure ionization mass spectrometry device(APIMS: UG-302P manufactured by Renesas Eastern Japan Semiconductor,Inc.).

Each sample is placed in a reactor tube manufactured by using anelectrolytically-polished pipe of SUS316L having a size of ½ inch. Ahigh-purity Ar gas having an impurity concentration of 1 ppb or less isused as a carrier gas. This is a system in which the Ar gas is made topass over the sample at a flow rate of 1.2 L/min and the amount ofmoisture released from the sample is measured by the APIMS.

A temperature profile at a time of measurement of the amount of moisturereleased from the ceramic film was set as follows. After the ceramicfilm was kept at a temperature of 25° C. for 10 hours, the temperaturewas increased up to 100° C. in 10 minutes. Then, the ceramic film waskept at 100° C. for 1 hour and 50 minutes. Thereafter, the temperaturewas increased stepwise by every 100° C. up to 500° C. During theabove-mentioned period, the amount of released moisture was measured.

FIG. 1 shows measurement data of the amount of moisture released from anY₂O₃ film. A horizontal axis shows a measurement time by the APIMS and avertical axis shows the number of water molecules released per unitarea. Using the sol-gel method, the samples were prepared by firing at300° C., 600° C., and 900° C. in the atmosphere and had a film thicknessof 1 μm.

FIG. 2 shows a graph plotting the amount of released moisture at eachtemperature rising stage with respect to temperature reciprocals (1/K)for 25° C., 100° C., 200° C., 300° C., 400° C., and 500° C. It wasconfirmed that an activation energy Ea of moisture desorption was 0.055eV regardless of a firing temperature. This suggests that a film qualityof a surface is not changed at all and only an effective surface area isdecreased. Further, it was confirmed that the amount of moisturereleased during the temperature rising up to 500° C. was 4.23×10¹⁸molecules/cm² for the samples fired at 300° C., 1.75×10¹⁸ molecules/cm²for the samples fired at 600° C., and 6.31×10¹⁷ molecules/cm² for thesamples fired at 900° C.

FIG. 3 shows a relationship between the firing temperature and theamount of moisture released when the temperature is raised up to 500° C.As the firing temperature is increased, a bonding strength at a grainboundary between Y₂O₃ crystal grains is increased and the effectivesurface area is decreased. Hence, it is understood that the amount ofreleased moisture is significantly decreased. Further, it is understoodthat, with the firing temperature not lower than 300° C., the amount ofmoisture released from the film is not more than 10¹⁹ molecules/cm².

Second Example

With respect to the samples 1 to 14 as a second example of the presentinvention, only a sol-gel film was formed on each of various kinds ofsubstrates as shown in FIG. 4, and evaluation was performed.

Third Example

With respect to the samples 15 to 29 as a third example of the presentinvention, a passivation film or the like was formed as a base on asurface of a substrate made of aluminum (Al) or stainless steel (SUS)and a sol-gel film was formed on the base, as shown in FIG. 5. Then,evaluation was performed. With respect to a SUS substrate of the sample15, a passivation film made of Cr₂O₃ was formed as a base on a surfaceof the substrate and a sol-gel film was further formed thereon. Then,evaluation was performed. With respect to an Al metal substrate of eachof the samples 16 and 17, an anodic oxidation film was formed as a baseby oxidizing Al of a substrate surface by electric field treatment in asolution and a sol-gel film was further formed. Then, evaluation wasperformed. With respect to an Al metal substrate of the sample 18, aMgF₂ film was formed as a base by fluoridizing a substrate surface, anda sol-gel film was further formed. Then, evaluation was performed.

Fourth Example

With respect to a composite of a sprayed film and a sol-gel film of eachof the samples 19 to 23 as a fourth example of the present invention,evaluation was performed on a composite film obtained by forming thesprayed film and thereafter forming the sol-gel film on a surfacethereof, as shown in FIG. 6.

Fifth Example

With respect to a composite of a sol-gel film and a sprayed film of eachof the samples 24 and 25 as a fifth example of the present invention,evaluation was performed on a composite film obtained by forming thesol-gel film as a base and forming the sprayed film thereon, as shown inFIG. 7.

Sixth Example

With respect to a composite with a sprayed film of each of the samples26 and 27 as a sixth example of the present invention, evaluation wasperformed on a composite film having a sandwich structure obtained byforming a sol-gel film as a base, forming a sprayed film thereon, andforming another sol-gel film on a surface thereof, as shown in FIG. 8.

Seventh Example

With respect to a composite with a sprayed film of each of the samples28 and 29 as a seventh example of the present invention, evaluation wasperformed on a composite film obtained by forming an anodic oxidationfilm as a base, forming the sprayed film thereon, and further forming asol-gel film formed on a surface thereof, as shown in FIG. 9.

Comparative Examples

In contrast, the samples 31 to 37 as comparative examples were made ofvarious substrates shown in the table of FIG. 10 and ceramic films wereformed by using the spraying method, a thermal CVD method, or aconventional sol-gel method. It is noted here that the conventionalsol-gel method is a method in which a structure and a purity of theceramic film are out of the scope of the present invention.

Hereinbelow, description will be made about verification and evaluationresults for the samples 1 to 29 as the examples of the present inventionand the samples 31 to 37 as the comparative examples.

(Film Purity)

Purity analysis was performed on each of the ceramic films. As a methodof analysis, GDMS (glow-discharge mass spectrometry) was used and, as ananalyzer, VG9000 manufactured by Fl. Elemental was used.

A plasma processing apparatus requires severer impurity control withminiaturization of a printed circuit and so on. Hence, in order toimprove a yield of an electronic component, a higher-purity ceramic filmis required.

The sol-gel film in each of the samples 1 to 29 as the examples of thepresent invention has a purity not less than 99%.

In contrast, the conventional sol-gel film in each of the samples 31 and32 as the comparative examples contains a large amount of alkali metalfor the purpose of technically enabling low-temperature film formation.Accordingly, the purity is about 85% and does not reach 98% or more. Thesprayed film in each of the samples 33 and 34 as the comparativeexamples has a purity of 99%. The CVD film in each of the samples 35 to37 as comparative examples has a purity of 95%.

(Etching Rate)

In a chamber of a parallel plate type RIE etching apparatus, a 6-inchsilicon wafer was placed and a mirror-polished test specimen was placedthereon. Then, a corrosion test was performed by plasma exposure inplasma of CF₄+O₂ for 10 hours. During the test, a part of a polishedsurface was masked with a polyimide tape and a silicon wafer. Adifference in level between the masked part and an unmasked part wasmeasured by a stylus method to calculate an etching rate.

Ceramics used herein as the examples is an oxide comparatively resistantagainst the plasma. Therefore, the amount of etching of its surface isvery small.

On the other hand, for the samples 31 to 34 as the comparative examples,Y₂O₃ and Al₂O₃ are similar to each other. For the films formed by theCVD method in the samples 35 to 37 as the comparative examples,variation is observed.

(The Number of Particles)

With respect to the silicon wafer after the above-mentioned plasma test,the number of grains having a size of 0.5 micron or more was measured byusing a particle counter (Surfscan6420 manufactured by Tencor).

With respect to the number of particles, an excellent result wasobtained by the sol-gel film which is a dense and flat film incomparison with other film formation methods. It is noted here that,since each of the samples 19 to 23 as the examples of the presentinvention has the sprayed film as the outermost surface, the number ofparticles is increased similarly to the samples 33 and 34 as thecomparative examples. However, in each of the samples 19 to 23 and 26and 27 as the examples of the present invention in which the sol-gelfilm is formed on a surface of the sprayed film, the number of particlesis decreased to about one third of that of the samples with the sprayedfilm only, although the number of particles is increased in comparisonwith the simple sol-gel films. Thus, by applying the sol-gel film, aneffect of decreasing the particles was obtained.

(Chlorine Gas Exposure)

Among electronic component manufacturing apparatuses, an apparatus formanufacturing a semiconductor device has an internal environmentconstantly exposed to a corrosion gas in each process. In view of theabove, a film in each of the examples was exposed to a Cl₂ gas toevaluate corrosion gas resistance.

As an evaluation method, a test specimen was placed in a sample mountingcell and a gas exposure test was carried out in an air stream containing100% Cl₂ gas and having a pressure of 0.3 MPa for 24 hours. Atemperature in the cell was kept at 100° C. A surface condition afterthe gas exposure was checked and presence or absence of surfacecorrosion or presence or absence of peeling was used as an evaluationcriterion.

With respect to each of the samples 1 to 29 as the examples of thepresent invention in which the sol-gel film was formed, no peelingoccurs and no change in surface condition was observed even after theCl₂ gas exposure. Thus, it was confirmed that, even if the Al metalsubstrate having low Cl₂ gas resistance was used as the base, formationof a dense sol-gel film prevented corrosion of the substrate anddurability and reliability as the member for a plasma processingapparatus were improved.

In contrast, in the conventional sol-gel films or the single layersprayed films in the samples 31 to 34 as the comparative examples, filmpeeling occurred. As a cause of this, it is presumed that, since thefilm itself has a large number of pores, a Cl₂ gas passing throughconsecutive pores directly corrodes the Al metal substrate to bringabout peeling of the film.

For the CVD films in the samples 35 to 37 as the comparative examples,no peeling of the film occurred. However, deterioration in quality of asurface of the film was observed.

(Film Formability to a Complex Configuration)

Judgment was made about whether or not film formation is possible onto acomplicated configuration, such as two or more steps and an innersurface of a box shape, an inner surface of a cylinder having a smalldiameter (for example, a gas pipe having an inner diameter of about 5mm), an inside of a porous body, and an inside of a fibrous filter.

In the examples 1 to 18, film formation was easily possible onto the twoor more steps and the inner surface of the box shape. In case of thecomposite film with the sprayed film in each of the samples 19 to 29 asthe examples of the present invention, film formability depends onwhether or not the sprayed film can be formed on an object surface.Therefore, those samples were excepted from the present evaluation.However, the sol-gel film could be formed throughout an entire surfaceonto a complicated configuration partly containing the sprayed film.

In contrast, in case of the comparative examples, the conventionalsol-gel film could flexibly be formed onto a comparatively complicatedconfiguration. However, in case of film formation with corners or asharp R shape, film peeling occurred due to low adhesion. In case of thesprayed film, film formation is performed only in a region where a framewith a sprayed material melted thereon can be linearly irradiated.Therefore, film formation was impossible onto a substrate with a shadedpart formed therein. The CVD film is not formed unless a surface onwhich a film is to be formed is completely exposed to a material gassupplied. Further, in case where a film formation surface has both aparallel plane and an orthogonal plane, film formation rates thereof areextremely widely varied. Therefore, uniform film formation wasimpossible.

Next, with respect to the inner surface of the cylinder having a smalldiameter, the inside of the porous body, and the inside of the fibrousfilter, a material solution (sol) was supplied to pass therethrough,dried, and thereafter fired. By using the sol-gel method, film formationwas possible onto those members having the above-mentionedconfigurations although it was impossible by the conventional technique.By the spraying method and the CVD method in the comparative examples,film formation throughout the entire surface was impossible inprinciple. Although film formation was possible by using theconventional sol-gel method, application to the member for a plasmaprocessing apparatus is difficult in view of purity and particles.

(Transmission, Transmittance)

Regarding the samples 10 to 13 as the examples of the present inventionand the sample 37 as the comparative example, the substrates themselvesexhibit translucency. Therefore, a transmittance at a visible lightwavelength between 400 and 800 nm was measured. In the measurement, aself-recording spectrophotometer (U-3500 manufactured by Hitachi, Ltd.)was used. Results of transmittances of the samples 10 to 12 are shown inFIGS. 11 to 13, respectively. As a comparative example, a transmittanceof the CVD film is shown in FIG. 14.

When a transmittance in a visible light range falls below 80%, a filmstarts to look cloudy in visual observation. Further, when thetransmittance falls below 60%, the film obviously looks cloudy. Thus, incase of application to a member required to have translucency, atransmittance not less than 80% is necessary in order to obtainexcellent translucency.

When the conventional technique is used, it is general that, as a filmthickness increases, a transmittance decreases. However, regarding thesol-gel film of the present invention, decrease in transmittance in avisible light range does not substantially occur if a film thickness isbetween 1 μm and 5 μm, as shown in FIGS. 11 to 13. Further, thetransmittance is kept at about 90% throughout an entire wavelengthrange. Considering that 4 mm thick quartz as a substrate has atransmittance of about 93% throughout an entire wavelength range, it isunderstood that a transmittance of the film alone is calculated to about97%.

In contrast, as shown in FIG. 14, the CVD film has a transmittance whichremarkably decreases to about 50 to 80% at a film thickness of 1 μm.Further, the sprayed film and the conventional sol-gel film do notexhibit translucency because a large number of pores are contained andthe film is thick.

(Comprehensive Evaluation)

With respect to the sol-gel single layer films or the multilayercomposite films containing no sprayed film in the samples 1 to 18 as theexamples of the present invention and the samples 31 to 37 as thecomparative examples, comprehensive evaluation of O is given to thosefilms which exhibit excellent plasma corrosion resistance represented byan etching rate of 10 nm/minute or less, which exhibit low dustingcharacteristics represented by the number of generated particles notmore than 50, and which can be processed into a complicatedconfiguration. Further, with respect to the composite films includingthe sprayed film combined with the sol-gel film in the samples 19 to 29as the examples of the present invention, comprehensive evaluation of Ois given to those films improved in the number of particles and inchlorine gas exposure characteristics in comparison with the simplesprayed film.

INDUSTRIAL APPLICABILITY

The present invention is applicable not only to an electronic componentmanufacturing apparatus, such as a semiconductor element and a liquidcrystal panel, but also to a member for use in all apparatuses forconducting plasma processing or the like with a corrosive atmosphere andto a method of manufacturing the same.

1. A member for a plasma processing apparatus, the member comprising asubstrate and a ceramic film formed thereon and having a purity not lessthan 98%, wherein: the ceramic film is constituted by grains having agrain diameter not greater than 50 nm, the amount of moisture releasedfrom the film being not more than 10¹⁹ molecules/cm².
 2. The member fora plasma processing apparatus as claimed in claim 1, the membercomprising, as the ceramic film, a sol-gel film formed by a sol-gelmethod.
 3. The member for a plasma processing apparatus as claimed inclaim 1, wherein: the substrate is made of metal, ceramics, glass, or acomposite material thereof; the ceramic film being a film comprising atleast one kind of element selected from group II-VI elements, groupXII-XIV elements, and rare-earth elements in the periodic table.
 4. Themember for a plasma processing apparatus as claimed in claim 1, whereinthe ceramic film is a film comprising at least one kind of elementselected from Mg, Al, Si, Ti, Cr, Zn, Y, Zr, W, and the rare-earthelements.
 5. The member for a plasma processing apparatus as claimed inclaim 1, wherein the ceramic film has translucency represented by atransmittance not less than 80% in a visible light range at a wavelengthbetween 400 and 800 nm when a film thickness is not greater than 5 μm.6. The member for a plasma processing apparatus as claimed in claim 1,wherein the ceramic film is formed in an oxygen-containing atmosphere ina temperature range between 250 and 1200° C.
 7. The member for a plasmaprocessing apparatus as claimed in claim 1, wherein the ceramic film hasa purity not less than 99.5%.
 8. The member for a plasma processingapparatus as claimed in claim 1, wherein: the substrate is made ofmetal; the substrate being provided with a film formed on its surfaceand obtained by passivation of the surface of the substrate.
 9. Themember for a plasma processing apparatus as claimed in claim 1, wherein:the substrate is made of aluminum; the substrate being provided with ananodic oxidation film formed on its surface.
 10. The member for a plasmaprocessing apparatus as claimed in claim 1, wherein: the substrate ismade of metal; the substrate being provided with a film formed on itssurface by heat treatment.
 11. The member for a plasma processingapparatus as claimed in claim 1, the member comprising, as the ceramicfilm, a sprayed film formed on the substrate by a spraying method and asol-gel film formed on the sprayed film by a sol-gel method.
 12. Themember for a plasma processing apparatus as claimed in claim 1, themember comprising, as the ceramic film, a sol-gel film formed on thesubstrate by a sol-gel method and a sprayed film formed on the sol-gelfilm by a spraying method.
 13. The member for a plasma processingapparatus as claimed in claim 1, wherein the substrate has a plate-likeshape having pores, a tubular shape, or a container shape.
 14. A methodof manufacturing a member for a plasma processing apparatus, comprisingthe step of forming a ceramic film having a purity not less than 98% ona substrate, wherein: the forming of the ceramic film is carried out sothat grains constituting the film have a grain diameter not greater than50 nm and the amount of moisture released from the film is not more than10¹⁹ molecules/cm².
 15. The method of manufacturing a member for aplasma processing apparatus as claimed in claim 14, wherein, as theceramic film, a sol-gel film is formed by a sol-gel method.
 16. Themethod of manufacturing a member for a plasma processing apparatus asclaimed in claim 14, comprising the steps of: forming the substrate madeof metal, ceramics, glass, or a composite material thereof; and forming,as the ceramic film, a film comprising at least one kind of elementselected from group II-VI elements, group XII-XIV elements, andrare-earth elements in the periodic table.
 17. The method ofmanufacturing a member for a plasma processing apparatus as claimed inclaim 14, comprising the step of forming, as the ceramic film, a filmcomprising at least one kind of element selected from Mg, Al, Si, Ti,Cr, Zn, Y, Zr, W, and rare-earth elements.
 18. The method ofmanufacturing a member for a plasma processing apparatus as claimed inclaim 14, wherein the ceramic film is formed in an oxygen-containingatmosphere in a temperature range between 250 and 1200° C.
 19. Themethod of manufacturing a member for a plasma processing apparatus asclaimed in claim 14, wherein the ceramic film has a purity not less than99.5%.
 20. The method of manufacturing a member for a plasma processingapparatus as claimed in claim 14, comprising the steps of: forming thesubstrate made of metal; and forming, on a surface of the substrate, afilm obtained by passivation of the surface of the substrate.
 21. Themethod of manufacturing a member for a plasma processing apparatus asclaimed in claim 14, comprising the steps of: forming the substrate madeof aluminum; and forming an anodic oxidation film on a surface of thesubstrate.
 22. The method of manufacturing a member for a plasmaprocessing apparatus as claimed in claim 14, comprising the steps of:forming the substrate made of metal; and forming a film formed by a heattreatment on a surface of the substrate.
 23. The method of manufacturinga member for a plasma processing apparatus as claimed in claim 14,comprising, as the forming of the ceramic film, the steps of forming asprayed film on the substrate by a spraying method and forming a sol-gelfilm on the sprayed film by a sol-gel method.
 24. The method ofmanufacturing a member for a plasma processing apparatus as claimed inclaim 14, comprising, as the forming of the ceramic film, the steps offorming a sol-gel film on the substrate by a sol-gel method and forminga sprayed film on the sol-gel film by a spraying method.